Apple Inc. CEO Tim Cook made a surprise appearance before the San Francisco Pride Parade on Sunday, paying tribute to those marching under the slogan ‘Apple Pride’ with 5,000 employees.

Cook posed for photos with Apple staff before the parade and tweeted a photo of Apple’s entry in the parade to his 536,000 followers on Twitter.

The 53-year-old attended the launch event for Apple’s marchers just days after CNBC host Simon Hobbs worried he had outed Cook, asking why there were not more openly gay CEOs of Fortune 500 companies.

Cook has never addressed the issue of his sexual orientation directly in public.

But in December last year during a speech on human rights at Auburn University he alluded to it, saying: ‘Since these early days, I have seen and have experienced many types of discrimination and all of them were rooted in the fear of people that were different than the majority.’

Cook has also been a vocal supporter of efforts to pass the Employment Non-Discrimination Act protecting LGBTI employees of US Government contractors from discrimination in the workplace.

On 17 June, he tweeted: ‘I applaud @WhiteHouse decision to ban #LGBT discrimination at fed contractors. House must act on #ENDA. A matter of basic human dignity.’

Cook was named number one in Out magazine’s most influential LGBTI people who aren’t officially out in 2011.

An earlier version of this article stated that Cook also marched in the parade but GSN has since learned that Cook only met with marchers at the pre-parade event.

Yoweri Museveni has told the backers of the Ugandan Anti-Homosexuality Bill that he would only sign it if a team of scientists could prove people were homosexual by choice, but they have not given up on trying to bring the bill back